PhpNativeTypeCaster incorrectly casts string "false" and "0" to true

Start in PhpNativeTypeCaster at the bool branch of the second pass, then inspect the existing 'string-to-bool' coverage in HydratorTest. Add coverage for string values 'false', 'true', '0', and '1', and verify that hydration returns the expected booleans without changing existing integer behavior.

Problem

PhpNativeTypeCaster casts scalar values to bool using native PHP cast (bool) $value.
This produces incorrect results for common HTTP input values.

HTTP query parameters and form data are always strings. When hydrating a DTO property
typed as bool, values such as "false" and "0" are cast to true instead of false.

Steps to reproduce

use Yiisoft\Hydrator\ArrayData;
use Yiisoft\Hydrator\Hydrator;

final class Input
{
    public bool $active = false;
}

$hydrator = new Hydrator();
$input = $hydrator->create(Input::class, new ArrayData(['active' => 'false']));

var_dump($input->active); // bool(true), expected bool(false)

The same issue occurs for query-string input in applications using yiisoft/input-http
with #[FromQuery] / #[FromBody] attributes.

Actual behavior

Input value	Cast result
"false"	true
"true"	true
"0"	true
"1"	true
""	false
0	false
1	true

Expected behavior

String representations of boolean values should be parsed explicitly, similar to
how integer and float strings are handled via NumericHelper::normalize():

Input value	Expected result
"false"	false
"true"	true
"0"	false
"1"	true

Root cause

In PhpNativeTypeCaster, the bool branch of the second pass uses unconditional
native cast:

case 'bool':
    if (is_scalar($value) || $value === null || is_array($value) || is_object($value)) {
        return Result::success((bool) $value);
    }
    break;

In PHP, any non-empty string is truthy when cast to bool:

(bool) 'false'; // true
(bool) '0';     // true

Context

• The current test suite only covers 'string-to-bool' with input '1' (HydratorTest).
  Cases 'false', 'true', and '0' are not covered.
• The official typecasting guide demonstrates bool hydration with integer 1,
  not string "false".
• yiisoft/validator provides BooleanValue rule for validation, but it does not
  transform raw values during hydration. Even when validation passes, PhpNativeTypeCaster
  still applies the incorrect cast afterward.

Suggested fix

For string and Stringable values, parse boolean keywords explicitly before
falling back to native cast. For example, filter_var($value, FILTER_VALIDATE_BOOLEAN, FILTER_NULL_ON_FAILURE)
may be used for string input, with null mapped to Result::fail().

Suggested test cases

• 'false' -> false
• 'true' -> true
• '0' -> false
• '1' -> true

Impact

Any application hydrating bool properties from HTTP input (query string, form data)
may silently receive inverted boolean values. This is especially dangerous for
filtering, feature flags, and opt-out parameters where false is the intended value.